Device for packaging and heat sealing of waste

ABSTRACT

A device for packing human waste in a tube includes a hollow mandrel and a supply of packaging tubes stored upon the exterior of the mandrel. The tube is fed upward across the upper mouth of the mandrel and downwardly through the interior of the mandrel. There is also provided a tube feeding means, positioned below the mandrel, as well as a pair of heat sealing jaws. A control means, in response to an activating device, initiates an operating cycle wherein the jaws are opened, the tube feeding means feeds a supply of tubing, the jaws are closed and locked, and then the jaws are heated to seal the tube.

United States Patent 1191 Forslund 1451 Sept. 30, 1975 [75] Inventor: Per Anders Goran Forslund, Nora,

Sweden Pactosan AB, Nora, Sweden Dec. 28, 19 /3 [73] Assignee:

[22] Filed:

21 Appl. No.: 429,155

[30] Foreign Application Priority Data Jan. 3, 1973 Sweden 7300052 [52] US. Cl 53/183; 53/180 [51] Int. Cl.'-'..... B6513 9/10; B65B 9/12; B65B 9/16 [581 Field of Search.... 53/193, 194, 180 M, 182 M, 53/373, 390,191, 192, 389. 183. 187. 3291 3.563.002 2/1971 Givin 53/390 X 3,583,126 6/1971 McCollough 53/373 X 3,617,696 11/1971 Reenstra et a1. 53/373 X 3,726,060 4/1973 McMillan 53/183 X Primary E.\'aminerTravis S. McGehce .-l.s'sislunr E.\uminerHorace M. Culver Attorney, Agent, or Firml-lane. Baxley & Spiecens [57 ABSTRACT A device for packing human waste in a tube includes a hollow mandrel and a supply of packaging tubes stored upon the exterior of the mandrel. The tube is fed upward across the upper mouth of the mandrel and downwardly through the interior of the mandrel. There is also provided a tube feeding means. positioned below the mandrel, as well as a pair of heat sealing jaws. A control means, in response to an aetivating device. initiates an operating cycle wherein the jaws are opened, the tube feeding means feeds a supply of tubing, the jaws are closed and locked, and then the jaws are heated to seal the tube.

7 Claims, 9 Drawing Figures US. Patent Sept. 30,1975 Sheet 1 of5 3,908,336

U.S. Patnt Sept. 30,1 975 Sheet 2 of5 3,908,336

P 30,1975 Sheet 3 of 5 US. Patent US. Patent Sept. 30,1975 Sheet40f5 3,908,336

U.S. Patent Sept. 30,1975 Sheet 5 of5 3,908,336

AH hm mm m A Tg O ONN DEVICE FOR PACKAGING AND HEAT SEALING OF WASTE The present invention relates to a device for solid or fluid waste, e.g., a dry toilet, in which one closed end of an endless tube or sleeve, of impermeable and flexible material, is inserted in a tubular funnel for receiving the waste and in which the other end of the tube is placed over the upper edge of the funnel and folded up to a great length, for storage outside and around the funnel.

The purpose of the invention is to achieve a solution of the problem of packaging waste in an entirely hygienic manner from e.g., industry, hospitals or homes. Made in the form ofa dry toilet, the invention is particularly useful in cases when there are no sewage facilities and when it is required that waste is collected in a system sealed off from the outer air According to the invention, a reliable solution of the sealing problem is obtained in that the waste and the sleeve are fed down a certain distance from the bottom of the funnel, towards a collection device located below, e.g., a sack, after which the sleeve is pressed together and heated electrically, so that a weld or transversal fusion of the sleeve material is obtained over the entire width of the sleeve, achieving an airtight heat sealing of the waste.

A special object of the invention is to find a solution of the problem of reliable feeding of a plastic tube without rollingup and jamming problems, and to achieve reliable operation of the welding jaws and an adaptation of the welding time with consideration to variations in the voltage obtained from the power supply, According to an embodiment of the invention described herein, the device is mounted in a housing or plate wrapping with cover and seat, under which a funnel rests on an intermediate partition provided with a hole through which the sleeve with waste passes. Under the intermediate partition there is a feeding device with welding jaws, which feeds the sleeve with waste and seals it. For the control of the entire flushing process there is also a control unit, of the plug-in type. The feeding device is provided with feeding discs on which operating cams are arranged, so that when the feeding discs rotate one turn during a working cycle, the operating cams are also turned, and actuate welding jaws,

so that the entire mechanical part of the flushing cy-,

cle" is carried out efficiently and reliably.

Further characteristic properties of the invention will be noted from the appended claims.

A complete dry toilet for packaging with heat sealing will be described in the following, with reference to six drawings and illustrations, in which FIG. 1 shows a complete toilet,

FIG. 2A shows the location and design of insert casing, funnel and feeding discs,

FIG. 2B is a fragmentary view of FIG. 2A showing structural details on an enlarged scale,

FIGS. 3A, 3B and 3C show different stages of the working principle of the device according to 'FIG. 1,

FIG. 4 shows a principle sketch in perspective of the feeding device and control unit,

FIG. 5. shows the electric wiring diagram, and

FIG. 6 shows the wiring diagram for the electronic time control unit.

The toilet shown in FIGS. ll, 2A and 2B is built up around an intermediate partition 10, on which a funnel 9 is mounted and inserted in a plate ring (the latter not shown). Around the entire unit there is an enclosing housing or plate wrapping 1.

FIGS. 1, 2A and 2B-show a complete toilet with an enclosure 1, which is provided at the top with a cover 2 and a toilet cover 3 with seat 4, and at the bottom with a bottom plate 17 with a recess for inserting a control unit 15, which slides along guide rails 18 and the front panel 6 which will cover the recess 5 in enclosure 1. On the front panel 6 the control devices required, such as the operation pedal 64 and the cable 8 for connection to the electric mains are mounted. In FIG. 2A, under the seat 4, a funnel 9 can be seen. In FIG. 2A there is also shown a central hole 16 in an intermediate partition 10 where four feeding discs lll4 are mounted in an insert casing 26, FIG. 2B, which has been given a special design as regards the mounting of the feeding discs 11-14 and the distance 28 between the discs in relation to the minimum diameter 27 of the funnel 9.

The guide rails 18 and the feeding device 19 are fixed to the bottom plate 17, and the feeding device is located directly over the central hole 16 in the bottom plate 17, through which the sealed tube or sleeve 20 with waste 21 (FIG. 3) passes on its way down to an underlying collection device (not shown).

The device functions in a way which will best be noted from FIG. 3A, in which, in the starting position, the sleeve 20, which is appropriately made of plastic or some other material suitable for the purpose is placed on and around funnel 9, as will best be seen from FIG. 3A, and extends from there between two sealing jaws 38, 39, which press the sleeve together and at the same time are made in such a way that they each have a horizontal part 23, which forms a bottom for said funnel 9, in which the waste 21 is to be placed. When this has been done, the jaws 38,39 are opened, i.e., the bottom of the funnel is removed, and the plastic sleeve 20 is fed down by e.g., the feeding discs 11-14, which work along the outer edges of the sleeve 20. The sleeve part will then be moved down past the feeding discs 11-14, as is shown in FIG. 3B. Thereafter the jaws 38, 39 can again be closed and sealing take place, as shown in, FIG, 3 C.

As shown in FIGS. 3A, 3B and 3C, the plastic sleeve 20 can appropriately be kept folded up around the funnel 9, advantageously in the form of an annular stack 24 with a central hole for the funnel 9, new plastic sleeve 20 then automatically being fed over the funnel 9 when a downward pulling force is applied to the sleeve 20.

The feeding device 19, the purpose of which is to feed said sleeve 20, which e.g., consists of plastic foil, and to operate the jaws 38, 39, is shown best in FIG. 4. The feeding device is built into a frame case with a central hole therethrough for the plastic sleeve 21) to pass through, and in which there is fitted a driving shaft 30 on which two feeding discs 11, 12 and two cam discs 31, 32 are fixed, one of which is concealed by the further feeding disc 12. At its farther end the driving shaft 30 is also provided with a fixed, sturdy gear wheel 35, which is in mesh with a similar gear wheel 36, which is fixed on another, driven shaft 37, on which two further feeding discs 13, 14 are attached in such a way that the feeding discs 11, 12 can roll against the feeding discs 14, 13, respectively, as the shafts 30 and 37 have opposite direetions of rotation. The driven shaft 37 is also provided with two fixed cam discs 33, 34, of which the cam 33 is concealed by the farther feeding disc 13.

The sealing jaws 38, 39 (see FIG. 4) are each mounted on pairs of arms 41, 42 and 43, 44, and one of the jaws 38 is provided with a second pair of arms 45, 46 on the inside of the outer pair of arms 41, 42. The arms 45, 46 are supported in the frame of the feeding device at their lower ends and are rotatably supported by means of rotatable spacing sleeves 47, 48 in the weldingjaw arms 41 and 42, respectively, which in their lower ends are rotatably fastened to two link arms 49, 50, of which the arm 49 has one of its ends fastened to a return spring 51 and the other arm 50 has one end fastened to a return spring 52 (not shown). The link arms 49, 50 have their other ends fastened each to its cam 54 and 53, respectively. On the other hand, the arms 43, 44 of the other jaw have their lower ends supported directly in the frame of the feeding device. Two double springs 55, 56, wound with double spring bodies, are mounted, one on either side of the feeding device, around fastening bolts (not shown) for the rotatable fastening in the lower of the pairs of arms 43, 44 and 46 and 45, respectively. The free ends of the double springs 55, 56 are compressed and fastened at a certain length up on the arms 44, 45 and 43, 46, so that these are given a torque, the pair of arms 44, 43 thus always being pressed towards the left and the pair of arms 45, 46 always being pressed towards the right. The cams 31 and 32 are positioned in such a way on the driving shaft that they will coact with the jaw arms 41 and 42, respectively, and the same applies to the earns 34 and in relation to the jaw arms 44 and 43, respectively.

The feeding device is also provided with an operating shaft 57, on which said cams 53 and 54 are mounted. The operating shaft 57 is also provided with a catch lever 58, which can run along a flange on the periphery of the gear wheel 36 and which, in a blocking position, can enter into a locking groove made in the gear wheel 36. The locking groove is made in such a way that the locking stud 59 can easily slide into and out of the blocking position, as shown in FIG. 4.

At its front end, the driving shaft 30 is provided with a shaft coupling 60, of conventional type, and can be coupled directly at the cam 31. The operating shaft 57 is also provided at its front end with a shaft coupling 61, of the same type, which can also be coupled directly to the cam 54. This serves the purpose of achieving a quick coupling to the motor 62 and the pedal shaft 63, the latter being located in the control unit 25.

The groove and the flange in the gear wheel 36 for the locking stud 59 are shown in FIG. 4 as being located on the inside of the gear wheel 36, but this groove can, 0f course, just as well be made on the outside of the gear wheel.

With the starting position shown in FIG. 4, the feeding device functions in the following way. When the operating shaft 57 is turned counter-clockwise by depressing eg a pedal 64, the earns 53 and 54 will move the jaw 38 towards the right (approx 3mm) as far as the arms and 46 and the earns 31 and 32 permit. At the same time the catch lever 58 is turned towards the right, so that e.g., the motor 62 can start to turn the shaft 30 counter-clockwise and thereby also the shaft 57 clockwise, and the locking stud 58 can then roll or slip along the flange of the gear wheel 36.

The cams 31, 32 and 34, 33, after having rotated approx 30 are now turned out of coaction with the jaw arms 45, 46 and 44, 43, and the springs55 and 56 move the jaws entirely apart. The feeding discs 31, 32 and 34, 33 then rotate, rolling against each other with the plastie sleeve in between them, and when a complete turn has been made, the plastic sleeve has been drawn down a distance corresponding to the circumference of the feeding discs. Just before the turn has been completed, the earns 31, 32 and 34, 33 have again entered into coaction with the arm jaws 45, 46 and 44, 43, and then press the jaws together so that only said play of 3 mm remains, owing to the fact that the operating shaft has not returned to its rest position. When the turn has been completed, the strong springs 51 and 52 forcefully retract the operating shaft 57, when the locking stud can again engagein its groove in the gear wheel 36. The spring 51' then forcefully compresses the jaws, by the links 49, being drawn towards the right and the jaw arms 41, 42 then turn about their upper suspension point at the spacing sleeves 47, 48, whereby the jaw 38 is moved towards the left, with great force, against the other welding jaw 39. It should be noted that the paris pairs jaw arms 45, 46 and 44, 43 then remain in a locked position.

The sealing can now commence, after a signal from a switch located outside of the feeding device. A flushing cycle has thus been completed, and the feeding device is ready for the next packaging operation.

In order to obtain trouble-free feeding of new plastic sleeve tube, without risk for unintentional winding up, it is essential that the feeding discs 11, 12 and 14, 13

l are set at a predetermined position in relation to the opening of the feeding device, as shown in FIG. 2B. In the opening, a plastic insert 26 is fitted, which to a certain extent (approx. 90) encloses the sides and periphcry of the feeding discs. The play between the feeding discs and the insert has been kept small, in order to prevent the plastic sleeve from coming in between (socalled wedge effect) at the same time as the shafts are also enclosed by the inner, flat walls of the plastic insert. The risk for a possible wedge effect is further reduced by the lower edge of the casings of the feeding discs having been displaced somewhat, (approx. 10) outwards, i.e., away from the center of the through hole.

In order to further reduce the risk for unintentional winding up, the inner sides of the feeding discs ll, 12 and 14, 13 can appropriately be made with a polished surface or with a radial, recessed groove in which a defleeting edge is caused by run.

As will best be noted from FIG. 2A, the feeding device is mounted on a bottom plate 17, and the frame or case 25 of the feeding device, at its lower edge, has

been provided with a pair of guide rails, which serve the The purpose of the control unit 25 is to drive and control the feeding device during the flushing process, and it therefore contains all of the electrical components, with the exception of the welding jaws. The control unit is made in the form of a plug-in" box with a front panel, on which certain controls are mounted.

The mechanical design of the control unit will be noted from FIG. 4, which also shows an arrangement, in which the box 25 contains a driving motor 62 with driving shaft and pin coupling 60, as well as a through pedal shaft 63 with pedal 64 and shaft pin coupling 61. The pedal shaft 63 is moreover provided with two round switching discs 65, 66, chamfered along a chord, intended for the control of two microswitches 67 and 68, respectively, for the control of the motor and the switch.

The electric wiring of the control unit 25 will best be noted from FIG. 5, in which the power supply cable is connected to a terminal block 69. Via a two-pole switch 70, an overload protector 71, a thermal switch 72, a microswitch 67 and a counter 73 are also connected in the circuit, which is connected to the driving motor 62. The counter 73 is then connected to a warning lamp 74 and an electronic control unit 75 (see FIG. 6) which in turn is connected to a microswitch 68 and a welding transformer 76, the secondary side of which is connected to a terminal bar 77, to which also the sealingjaws 38 and 39 are connected. The terminal bar 69 is provided with extra outlets for an external warning lamp.

As will be noted from FIGS. 1 and 5, certain components have been placed on a control panel 6, which can be seen at the lower part of one side of the toilet, viz. the foot pedal 64, the warming lamp 74, the power supply switch 70, the resetting button for the overload pro tector 71, the power supply cable 8 and a pointer with scale for the counter 73. This scale is graduated from zero (lowermost, at 6 oclock) and with rising decades clockwise approx. of a full turn to a final figure (located at approx. 2 oclock) where there is also a stop screw mounted, to stop the turning, which must be done by hand, to set the pointer and thereby thecounter to the full position. The highest decade, in the foregoing called the final digit, serves as an indication as to how many times of use remain before the collection sack is filled or all of the plastic foil has been used. The pointer, which serves as a knob for resetting the counter, is moved a short step counter-clockwise by the counter for each time of use, and thus, constantly indicates how many times of use remain.

During a flushing operation the control unit 25 functions in the following way. When the pedal 64 is depressed, the microswitch 67 closes the circuit to the motor 62 and the counter, provided that the switch 70 is closed and the overload protector 71 or the thermal switch has not been triggered, and that the counter 73 has not broken the circuit because of an empty cassette of plastic tube, in which case the warning lamp is lit. Pulses are now sent through the microswitch 68 to the electronic control unit 75, to sense the prevailing circuit voltage and to prepare a suitable sealingpulse.

The pedal remains in the depressed position throughout the entire procedure, and the feeding device goes through the whole of its operating cycle. It is only when the procedure has been completed, and the pedal shaft has returned to its starting position, that the feeding of the plastic sleeve with waste is completed and the sealing jaws are pressed together and ready for heating. When the pedal shaft suddenly returns, the microswitch 67 breaks the circuit to the motor 62 and the counter 73, and at the same time the microswitch 68 via the control unit triggers an appropriate primary voltage pulse to the sealing transformer 76. An operating cycle has now been completed, and the device is ready for the next packaging.

If an object which is too large is put into the toilet, the jaws 38 and 39 cannot be moved together by the earns 31, 32 and 34, 33 on the driving shaft 30 and the driven shaft 57, respectively, without the motor 62 being blocked. This has the consequence that the microswitch 67 will never break the circuit, which will have the result that the motor of the counter 73 will continue to befed with voltage until this has gone down to zero. The circuit to the driving motor 62 of the toilet will then be broken, and the warning lamp 74 will light The electronic control unit 75, which can best be seen in FIG. 6, is built up on a plate, which is provided with terminals 78 and 79 for connection of the mains voltage to a power transformer 80, which has a 12 volt winding on its secondary side, which via a fuse 81 feeds a rectifier bridge 82 with a smoothing capacitor 103. This then feeds a sealing control circuit consisting of a potentiometer 83, a feeding resistor 84 and a capacitor 85, which together with the resistors 83 and 84 form the charging and discharging circuit, the time constant of which influences the pulse length of the sealing. Further, the base of the transistor 86 is fed from the rectifier bridge via the feeding resistor 87. In a circuit for sensing the voltage of capacitor there is a zener diode 88 and a resistor 89 for feeding of the base of a transistor 90, which is connected directly to the base of still another transistor 91, which is connected in series with a relay 92 and two terminals 93 and 94, between which the microswitch 68 is connected. The base of the transistor 91 is fed via a resistor 95 from the terminal 93. The relay 92, which is provided with a diode 104 parallel over the operating winding, has its operating contact connected between two terminals 97 and 98.

There is also a delay circuit connected from the ter minal 93 via a diode 99 to a capacitor 100, which via a resistor 101 is connected with the base of a transistor 102, the collector of which is directly connected to said transistor 86.

During a working operation, the electronic control unit 75 functions in the following way. In the starting position the microswitch 68 is in the closed position, according to FIG. 6. The capacitor is then charged via the terminals 94 and 93, the switch 68 and the diode 99, which involves that the base of the transistor 102 receives voltage via the resistor 101. As the collector of the same transistor receives voltage via the resistor 87, the transistor 102 will conduct and the voltage on the collector will be low. This, in turn, involves that the transistor 86 will be cut off due to low base voltage and that the voltage at point P will be high (approx. 12V) because of the capacitor 85 having been charged via the resistors 83 and 84. The voltage over the zener diode 88 will not exceed the zener voltage (6, 8V) and therefore reverse voltage flows through the diode and the resistor 89, and the base voltage of the transistor 90 will then be high. The transistor 90 then takes current via the resistor 95, and the voltage on the base of the transistor 91 is then low, and which then chokes the current to the relay 92, which is thus switched off.

When the microswitch 88 breaks the voltage supply at the turning of the operating shaft 57, the relay will also be without feed voltage, and also the transistors 91 and 90. In this situation the diode 99 now blocks the discharging of the capacitor 100 via the relay 92 or the transistors 91 or 90. Instead, the capacitor 100 now starts to discharge via the resistor 101 and the base circuit in the transistor 102. This involves that the relay 98 will not make contact if the microswitch 68 shortly after first having broken the circuit should make contact again, owing to e.g. slipping on the operating pedal. The capacitor 100 and the resistor 101 thereby function as a safety delay device, to prevent unnecessary extra welds.

When the capacitor 100 has discharged so much that the base voltage on the transistor 102 has gone down to cut off, the base voltage on the transistor 86 will rise, so that this will light, and the voltage in point P will then go down to zero, through the discharging of the capacitor 85, which gives increased current and voltage drop in the resistors 83 and 84. The diode 88 will then not obtain the zener voltage and the diode will not transmit current, and the voltage on the base of the transistor 90 will thus disappear, with the result that voltage on the base of the transistor 91 would be high if the feed current had not been broken. For the same reason the relay 92 cannot now make contact. However, this can take place as soon as the switch 68 connects the feed voltage when the operation has been completed, when the transistor 91 receives voltage on the base via the resistor 95 and lights, and the relay 92 then receives full voltage. When this makes contact, the current to the sealing jaws is switched on, and the sealing pulse is started. A current now flows through the positive pole of the rectifier 82 via the terminals 94 and 93, the operating winding of the relay 92 and the transistor 91 to earth. The purpose of the diode 104 is to serve as a transient protector (spark extinguisher) for transistor 91 and the diodes in 82, and also to serve as a so-called speeding diode by rapidly reducing the voltage over the operating coil 92 when the transistor 91 closes the thereby prevent so-called sneaking return of the relay armature, which would result in burning out of contacts.

At the instant when a positive voltage returns to the terminal 93, when an operation has been completed, the capacitor 100 is recharged, and the transistor 102 conducts again and the transistor 86 is cut off. It is now possible for the capacitor 85 to start to charge via the resitors 83 and 84. The rate of speed at which this charging takes place depends upon the input voltage and the setting of the potentiometer 83. The time that elapses before the zener voltage for the diode 88 has been reached will then determine the duration of the welding pulse, because of the fact that as soon as the voltage of the capacitor 85 has reached zener voltage (here 6, 8V), the diode will light and give voltage to the base of the transistor 90 which, in turn, lights and gives a low voltage to the base of the following transistor 91. The latter will then be cut off and the relay 92 will fall out, and the sealing will be discontinued.

The sealing time will then be automatically adapted to the prevailing circuit voltage inversely in order to achieve a uniform temperature of the welding jaws and, accordingly, a uniform quality of the weld seams.

In addition to the fact that the system has a plug-in unit constitutes an advantage from the point of view of manufacturing, it is also a great advantage when cleaning and servicing. If, for any reason, the toilet should be contaminated, after having removed the plug-in unit, it can be flushed internally directly with water without causing any damage.

All differences in design due to different driving sources will affect only the plug-in unit. In another em bodiment, the control unit can, for instance, be driven direct from a direct current battery which, in principle, does not change the way in which the unit works. The mechanical connections to the rest of the device and the connections to the sealing jaws are identical, which gives full interchangeability between different plug-in units.

All of the units described can individually be applied to other types of packaging devices.

I claim:

1. Device for packaging of materials in a tube, particularly human waste in a plastic tube, comprising in combination: a vertically disposed hollow mandrel, a supply of packaging tube stored upon the exterior of and fed upwardly across the upper mouth, of said mandrel and downwardly through the interior thereof, a tube feeding means positioned beneath said mandrel, said tube-feeding means being provided with two paral lel geared-together shafts straddling said tube, a motor for driving said shafts, a pair of reciprocatable transversal heat-sealing jaws straddling said tube and coacting with said shafts, a controllably activatable control unit for causing said motor to rotate for an operating cycle, mean responsive to the rotation of said motor for opening and then partially closing said jaws, means responsive to the rotation of said motor for activating said tube-feeding means to feed a predetermined length of said tube while said jaws are open, an operating mem ber that upon operation activates said control unit, means responsive to said operating member and operable after completion of said operating cycle for said tube-feeding means for pressing said jaws together, and means operable when said jaws are together for transmitting an energy impulse to said jaws for forming a transverse seal across said tube.

2. The device of claim 1, wherein said shafts of said tube-feeding means are each provided with a pair of feeding discs and further comprising cams on said feeding discs, and a pair of swingable arms coacting with said cams for supporting said heat-sealing jaws.

3. The device of claim 2 wherein said pairs of arms are so disposed that said jaws in said starting position are separated from each other by approximately 3 millimeters.

4. The device of claim 2 further comprising a third pair of swingable arms disposed as a lever acting on one of said jaw-supporting pairs of arms and a link mechanism for connecting said third pair of swingable arms with said operative member so that said jaws can be firmly pressed together by operation of said member.

5. The device of claim 2 wherein the inner diameter of said mandrel at its outlet end is greater than the distance in the axial direction between said pair of feeding discs on each shaft of said tube-feeding means.

. 6. The device of claim 5 further comprising a tubeguide disposed beneath the outlet end of said mandrel for screening off the plastic tube from the elements of i said feeding means except. where said feeding discs grip impulse in accordance therewith so that the energy content of said energy impulse is within certain limits independent of the input voltage. 

1. Device for packaging of materials in a tube, particularly human waste in a plastic tube, comprising in combination: a vertically disposed hollow mandrel, a supply of packaging tube stored upon the exterior of and fed upwardly across the upper mouth of said mandrel and downwardly through the interior thereof, a tube feeding means positioned beneath said mandrel, said tube-feeding means being provided with two parallel gearedtogether shafts straddling said tube, a motor for driving said shafts, a pair of reciprocatable transversal heat-sealing jaws straddling said tube and coacting with said shafts, a controllably activatable control unit for causing said motor to rotate for an operating cycle, mean responsive to the rotation of said motor for opening and then partially closing said jaws, means responsive to the rotation of said motor for activating said tube-feeding means to feed a predetermined length of said tube while said jaws are open, an operating member that upon operation activates said control unit, means responsive to said operating member and operable after completion of said operating cycle for said tube-feeding means for presSing said jaws together, and means operable when said jaws are together for transmitting an energy impulse to said jaws for forming a transverse seal across said tube.
 2. The device of claim 1, wherein said shafts of said tube-feeding means are each provided with a pair of feeding discs and further comprising cams on said feeding discs, and a pair of swingable arms coacting with said cams for supporting said heat-sealing jaws.
 3. The device of claim 2 wherein said pairs of arms are so disposed that said jaws in said starting position are separated from each other by approximately 3 millimeters.
 4. The device of claim 2 further comprising a third pair of swingable arms disposed as a lever acting on one of said jaw-supporting pairs of arms and a link mechanism for connecting said third pair of swingable arms with said operative member so that said jaws can be firmly pressed together by operation of said member.
 5. The device of claim 2 wherein the inner diameter of said mandrel at its outlet end is greater than the distance in the axial direction between said pair of feeding discs on each shaft of said tube-feeding means.
 6. The device of claim 5 further comprising a tube-guide disposed beneath the outlet end of said mandrel for screening off the plastic tube from the elements of said feeding means except where said feeding discs grip the plastic tube with small areas of their circumferences.
 7. The device of claim 1 wherein said control unit comprises a voltage-sensing circuit for sensing an input voltage for controlling the period of time of said energy impulse in accordance therewith so that the energy content of said energy impulse is within certain limits independent of the input voltage. 